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threaded steel pipe for a suction line

I had a customer today that wanted me to make a copper to steel transition .

This is for a rig to cool natural gas so they can crack it.

Evap temp is gonna run -10f

They wanted to run the suction line in schedule 80 threaded pipe . I said not a good idea ,may hold at first bit after cycling the machine I was afraid thermal expansion and contraction would cause leaks . They are now going to socket weld it . They wouldn't let me run copper as they already have pipe and firings and say they are close to losing money on this deal.

Gas stripper

Check out the pics on my profile. We built this stripper a few years ago, and the only leak source was the threaded pipe plugs on the chiller barrel. This stripper runs at -25 deg F. Stick with all copper, or walk away. You aren't talking that much piping, are you?

Check out the pics on my profile. We built this stripper a few years ago, and the only leak source was the threaded pipe plugs on the chiller barrel. This stripper runs at -25 deg F. Stick with all copper, or walk away. You aren't talking that much piping, are you?

yep, they are assuming all responsibility...i made them some copper to steel transitions using 45% blue rod....they said they would socket weld the rest...im not crazy about it.

Female copper adapter use a file to knock down ridges on male pipe thread on schedule 80 steel pipe. Use silver solder flux like pipe dope. screw in steel to copper do not over tighten. Use Silver 45 or blu rod. heat steel pipe first to tranfer heat into copper. Make braze joint. ridges knocked down on threads will allow 45 to flow. You can try all kinds of pipe dope after a year or so they will all leak due to different expansion of copper and steel.

My thoughts on this (which are not worth much haha) if it is all steel it will expand and contract at a similar rate. Steel threaded to steel would expand and contract together. Copper and steel threaded I would think that would be a good leak zone. Kind of like aluminum intake manifold on a cast block. Dont they have issues with that sometimes. If it works good this should be the new craze because steel is cheaper

Assuming that the inside of the pipe is clean, the only thing wrong with a socket-welded steel suction line is that it will rust if not prepped and painted, and there's a lot of pressure drop thru a short radius weld 90.

As for cost, it will offset between cost of copper and the time it takes to run weld pipe.

My thoughts on this (which are not worth much haha) if it is all steel it will expand and contract at a similar rate. Steel threaded to steel would expand and contract together. Copper and steel threaded I would think that would be a good leak zone. Kind of like aluminum intake manifold on a cast block. Dont they have issues with that sometimes. If it works good this should be the new craze because steel is cheaper